Combined propulsion and steering apparatus for vessels



April 0, 196.5 0. BACKHAUS ETAL 3,179,081

COMBINED PROPULSION AND STEERING APPARATUS FOR VESSELS Filed Nov. 8, 1963 2 Sheets-Sheet l PRIOR ART 5 iiiii' April 20, 1965 o. BACKHAUS ETAL 3,179,081

COMBINED PROPULSION AND STEERING APPARATUS FOR VESSELS I Filed Nov. 8, 1963 2 Sheets-Sheet 2 54 v .24

'l I 45 FIG. 9 5% United States Patent 3,179,031 COMBINED PROPULSION AND STEERING APPARATUS FGR VESSELS Otto Backhaus, Hamburg, Germany, Ernest K. Roscher, Leonardo, NJ and Ludwig Kort, deceased, late of Hannover, Germany, by Ruth Burner-Kort, heir, Kassel- Kirchditmold, Germany, assignors to Ingenieur Buro Kort, Hamburg-Wandsbek, Germany, a corporation of Germany 7 Filed Nov. 8, 1963, Ser. No. 322,552 7 'Clair'ns. (Cl; 115-42) This is a continuation in part of our application Serial No. 71,656 filed November 25, 1960, and now abandoned. The present invention relates generally to propulsion and steeringof screw-propeller marine craft and more particularly to an apparatus for combined propulsion and steering of deep water vessels comprising an improved Kort nozzle rudder.

Kort nozzle systems of propulsion are well-known in the marine art. Such systems are disclosed, for example, in the United States Patents 2,139,594 and 2,566,525. These known systems have progressed from the use of a tubular nozzle ringarranged around the turning disc of a screw propeller and mounted stationary relative to the vessels bull to the Well-known Kort nozzle rudder which provides an apparatus in which the nozzle ring is pivotally mounted and angularly rotatable horizontally around a stationary screw propeller turning disc within a limited range of rudder angles to the propeller.

Other combined propulsion and steering apparatus for vessels are known. Some of these devices make use of a shroud around the propeller. The propeller is driven by an electric motor mounted below the surface of the water a short distance behind or in front of the propeller.

or inside of the shroud. The shroud in these devices, however, is not shaped as an effective Kort nozzle ring and generally such apparatus are applied only as an auxiliary device exclusively for improving the steering characteristics of the rudder and are not used for main tions per minute such an electric motor would have to be immense. Aside from construction problems there would be the usual DC. motors insurmountable problems attendant because of the motors constantly immersed position. This limits the use of direct electric drive to A.C. motors only which, however, operate effectively only at a highnumber of revolutions per minute and moreover, permit practically no adaptability to changes of the rotary speed necessary for safe maneuvering of a vessel. For these reasons this type of known system has been limited to the above-mentioned auxiliary use only.

It is a principal object of the present invention to provide an improved Kort nozzle rudder drive for combining the main propulsion of vessels with improved steering capabilities in ahead and astern operation.

Another object of the invention is to provide, a cornbined propulsion and steering apparatus with greatlyimproved flexibility of control and efficiency of performance of the apparatus itself andwith improved propulsive effect and transverse steering forces at all rudder angles.

Still another objectis to provide a drive and steering apparatus permitting optimum use of the inner space of the vessels hull relative to the required machinery spaces.

The important features of the invention are the provision of a tubular nozzle ring shaped according to the basic requirements'of an eifective Kort nozzle rudder in which is mounted and carried a large diameter screw propellerrotatable internally of the nozzle ring. The screw is driven by a rather small and light reversible high-pressure hydraulic motor arranged forward of the propeller and provided with a short shaft carrying the propeller. The motor is covered with a housing or covering having outersurfaces shaped and faired and flowing towards the rear for reducing the resistance of the water flowing around it toward the mouth of the nozzle and toward the propeller and means to rotate these elements as a combined unit arranged outside of the vessels hull for pivotal movement around the rudder axis of the vessel through 360 degrees.

Other features and advantages of the 'apparatus in-accordance with the present invention will be better understood as described in the following specification and appendedclaims, in conjunction with the following drawings in which:

FIGS. 1-4 inclusive are diagrammatic illustrations of a known Kort nozzle rudder and are illustrative of the operation of this known apparatus;

FIGS. 5-8 inclusive are diagramamtic views of an improved nozzle rudder according to the invention and are illustrative of the operation of a nozzle rudderin accordance with the invention;

FIG. 9 is avertical section viewofan apparatus in accordance with the invention;

FIG. 10 is a median section view of a portion of the apparatus illustrated in FIG. 9.

As well known from Newtons first law a propeller develops thrust by accelerating a certain quantity of water. Anunshrouded propeller causes the water accelerated by it to have a maximum water velocity some distance astern of it. Therefore, by the law of continuity the jet or slipstream must contract behind the, propeller. Since the propeller has to pump all the water through an area havinga cross section smaller than its own the thrust produced per unit of power is smaller than if contraction of the jet did not exist.

In the known Kort nozzle rudder the propeller is shrouded. Asillustrated diagrammatically in FIGS. 1-4, inclusive, a tubular nozzle ring 1, which is of the type employed in the apparatus accordingto the invention and later described in complete detail, shrouds a large diameter screw 2 connected to a shaft 3 driven from internally of a vessel, the hull 4 of which is illustrated fragmentarily and schematically. The nozzle 1 of theKort nozzle rudder prevents contraction of the jet behind the propeller 2. The water flow is illustrated by solid lines and in ahead operation enters the nozzle 1 through a flared entry or mouth as illustrated and leaves the propeller with a cross sectional area equalto or, in some cases, larger than its disc area. Thus, the accelerated. water overcomes less resistance and in comparison with an unshrouded propeller at the same engine power and revolutions accelerates a greater quantity of water which is given a greater acceleration than possible by an unshrouded propeller so that a greater thrust will result. This accounts for the material thrust increase possible with'a Kort nozzle. This increase in thrust reaches a maximum at slow speeds of ahead travel and the increased thrust reaches a value of about fifty (50) percent over that produced by an open propeller under the same operating conditions.

The known Kort nozzler rudder, however, has limitations in that the nozzle rudder 1 is pivotally mounted on the outside of a vessel for movement relative to the screw propeller for steering and the maximum rudder angle employable is in the order of 35 to 50 degrees. Thus, although the known Kort nozzle rudders improve the turning circle of a given vessel over other rudders in the order of forty percent, the system is still unable to take full advantage of the thrust of the slipstreamof the propeller for steering purposes through 360 degrees.

The known Kort nozzler rudder, however, has additional limitations as to its performance with respect to its development of driving thrust relative to the transverse forces produced for steering. In a centered rudder position, as shown by FIG. 1, the gain in thrust at reduced speeds and full engine power for example, on harbor tugs when assisting in the docking of a large ship, will be about 40 to 50 percent. When the rudder is at various rudder angles in ahead operation as illustrated in FIG. 2, the

thrust and the available transverse forces for steering will fall off quickly with increasing rudder angles. When steering during ahead travel the maximum transverse steering forces will be reached at rudder angles of about 25 to 30 degrees but at very reduced available thrust. During astern operation the water must pass through the nozzle ring in an opposite direction as illustrated in FIGS. 3 and 4. Even without rudder angles as illustrated in FIG. 3 the thrust performance is reduced to about 60 to 70 percent of the ahead performance and at rudder angles, as shown in FIG. 4, the available thrust further decreases and moreover the direction of the water jet does not follow the axis of the nozzle ring corresponding to the angular position of the rudder with respect to the drive shaft of the propeller and the longitudinal axis of the ship but forms therewith a much smaller angle thereby resulting in a further reduction of the available trans verse steering forces.

The stream lines illustrating the water movement, as illustrated in FIGS. 2 and 4, and the angular and off-center position of the propeller with respect to the axis of the nozzle ring indicate quite clearly the reasons for the limitations and the much reduced performance. It will also be understood that the losses increase rapidly when the larger rudder angles are used. Because of these limitations of the known Kort nozzle rudder drive, though frequently applied in practice, a considerable amount of time has been spent in search of a solution to the above limitations and permitting unimpaired use of the nozzles thrust with increasing effect at the largest possible rudder angles and for propulsion as well as for steering. In connection with a solution it was also necessary for deep water vessels that a rather large engine power had to be applied driving a large diameter propeller turning at comparatively small revolutions per minute and that the transmission of the engine power to the propeller had to be independent of a tail shaft extending outwardly from the inside of the ship. Thus a possible solution required that the propeller had to be actuated by an independent motor directly connected to the nozzle ring and capable of following all of its angular movements. Moreover, such a motor had to be small and light despite of the large power requirements and had to be suitable for operating reliably without attendance for long periods of time in a fully submerged state.

An apparatus meeting the above requirements and according to the invention is illustrated diagrammatically in FIGS. 5-8 inclusive. The same reference numerals are employed as heretofore to denote similar parts in the drawings. An improved Kort nozzle rudder according to the invention comprises a Kort nozzle ring 1 internally of which is mounted a screw propeller of relatively large diameter in a fixed position relative to the axis of the nozzle 1 as later described hereinafter at length.

The reversible propeller 2 is reversibly driven selectively by a high pressure hydraulic motor 5 illustrated diagrammatically in FIGS. 58 and later hereinafter described. The tubular nozzle ring 1, the propeller 2 and hydraulic motor 5 are mounted externally of the hull 4 and pivotally suspended therefrom as later described, and are rotatable as a unit as illustrated in FIGS. 5-8. The nozzle it and propeller 2 have the same positional relationship through 360 degrees of rudder angle thereby constantly maintaining the optimum characteristics of fixed relationship between the propeller 2 and the nozzle 1.

In the drawing FIGS. 5 and 7, illustrate ahead and astern operation of apparatus according to the invention. The water always enters the turning disc or plane of the propeller substantially normal thereto so that a greater quantity of water can be accelerated at a higher velocity than possible heretofore. Moreover, the slipstream or jet discharged from the propeller 2 and nozzle 1 is constantly maintained at its maximum cross sectional area so that the maximum thrust available from the apparatus is maintained regardless of angular position of the nozzle rudder. Moreover, the water is constantly in contact with the inner surfaces of the nozzle regardless of ahead or astern operation thereby precluding the formation of eddies or turbulence and the resultant development of drag and loss of power output.

According to the invention, as illustrated in FIGS. 6-8, a'wide range of rudder angles, through 360 degrees, is possible. For example, a rudder angle is illustrated in FIG. 7 in which the position of the nozzle rudder 1, 2, 5 is degrees from the position illustrated in FIG. 5 so that the Water enters the nozzle 1 through the normal forward water entry opening similarly to ahead operation. This type of operation is to be compared with FIG. 3 in which the water enters through an exit opening of the nozzle 1 or discharge end of the nozzle 1 and flows toward the propeller through a substantially cylindrical exit zone so that the water cannot be additionally accelerated as is possible in the invention as illustrated in FIG.- 7. Moreover, the quantity of water moved through the nozzle rudder, according to the invention, is greater and receives greater acceleration than is possible in the known Kort nozzle rudder since in the invention the water enters a convergent entry zone of the nozzle in which it is accelerated as hereinafter explained.

The maneuverability of a vessel is greatly enhanced by the apparatus according to the invention. As indicated heretofore, a greater thrust is developed by the apparatus than heretofore. The unimpaired and increased thrust due to the properly shaped nozzle ring combined with a suitably shaped and properly placed propeller, held in a iven fixed position relative to the nozzle, forming an integral part of the invention, permits a maximum output of thrust. Moreover, the many angular positions to which the apparatus can be disposed permits an infinite number of rudder angles, for example, as illustrated in FIG. 8, to rapidly move the stern of the hull 4 clear of a dock, not shown. The turning circle of a given vessel is greatly reduced when the apparatus according to the invention is used as against known propulsion and steering apparatus.

Details of apparatus according to the invention are H lustrated by way of example in FIGS. 9 and 10. While the invention will be discussed with respect to a single nozzle rudder it will be understood that vessels can be provided with a plurality of apparatus according to the invention. In the improved Kort nozzle rudder the tubular nozzle ring 1 is pivotally supported from :the hull 4 illustrated fragmentarily by a tubular support member 6 pivotally rotatable as hereinafter described and rotatable through 360 degrees. The nozzle ring 1 is profiled and has the walls'thereof constructed with airplane airfoil profiles and defining well rounded front and rear a entering adges la, 11) respectively on the nozzle rin The. rear edge lb need not be well rounded, however,

rounding the rear edge is particularly useful for astern I operation, for example in an emergency, when there is not suflicient time to rotate the nozzle ring 180 degrees and a vessel must be quickly stopped. The nozzle ring 1 has inner surfaces defining a substantially cylindrical portion 10 in which the cross sectional area does not change materially along the longitudinal axis of the tubular nozzle ring 1. The cylindrical portion llc is provided with a rear exit opening 1d. The inner surfaces defined by the walls of the nozzle ring are enlarged with distinctly increasing cross sectional areas relative to the cylindrical portion lc to define a water entrance portion 1a having an entrance opening if which is substantially larger in cross sectional area than the exit opening 1d.

The propeller Z is a largediameter propeller having a plurality of blades 7. The propeller 2 is positioned internally of the nozzle ring 1 in an axial position therein such that its turning disc is substantially in an area or zone of juncture of the entrance portion 12 and cylindrical portion 10 as illustrated. The internal dimensions of the nozzle ring it are such as to provide the smallest possible clearance between the tips of the propeller blades 7 and the inner surfaces of the tubular nozzle ring. The water entering theturning disc of the propeller has been increased in quantity and accelerated by the entry portion of the nozzle ring, as later described, and by the propeller blades '7 and leaves the propeller through the substantially cylindrical zone lc, without further increase of speed, as a Water jet or slipstream whose cross sectional area does not change materially along the longitudinal axis of the cylindrical portion lie.

The screw 2 is reversibly driven by the hydraulic motor operable at high fluid pressures. The motor comprises, for example, a rotor assembly 9 to which is fixed a short propeller shaft 19 rotatab'ly journaled on a rotor support bearing ill and an axial thrust bearing 13 forwardly of the rotor assembly 9. The rotor 9 and shaft it) are enclosed in a fihid-tight motor casing or housing 15 with the motor shaft extending a short length outwardly thereof through a fluid-tight rear opening 16. The hydraulic motor, housing and the propeller in. as-

I sembly therewith are mounted coaxially with the tubular nozzle ring 1 in a fixed relative position by means of a plurality of radially extending, angularly spaced stream: lined braces or struts 2t 21.

The motor and motor housing are disposed forwardly of the propeller 2. The motor housing 15 is fairedand tear drop or torpedo-shaped and is substantially circular in cross section along its length in order not to impede the flow ofwatertowards the propeller. The motor housing. has a rear portion having outer surfaces con-r verging toward the propeller disc. These converging outer surfaces define in conjunction with the inner surfaces of the water entrance portion la a continuously converging annular water entry zone between the entrance opening or month if of the nozzle ring and the turning disc of the propeller for continuously accelerating the entering water. The motor housing 15 extends axially forwardly of the entrance opening if and has its major cross sectional areas forward of the entrance opening 1 The hydraulic motor is reversibly driven by hydraulic fluid provided through a fluid pressure system, for example, a hydraulic pressure" system comprising supply and return lines 25, 31 through which fluid under pressure is applied to the motor for reversible operation thereof. The fluid lines are preferably disposed inside of the. hollow iaired strut 23 so that they are well pro teoted. These. lines are connected in known manner to swivel connection means shown diagrammatically as pivotally mounted plates 32, 33 of a distribution box 34 permitting angular movement relative to the vessel of the lines 29, El rotationally, jointly with the motor, propeller, and nozzle ring i about a vertical, pivotal axis.

h The connection permits movement relative to stationary hydraulic supply and return lines 35, an internally of the vessel and connected to a source for fluid pressure within the hull 4 of the ship or vessel, as for example, a pump, not shown. The plates 32, 33 form two separate fluid-tight compartments in the distribution box 3-4 respectively in cormnunicationwith the lines 29, 36 and lines 33, 35 as illustrated in FIG. 10 so that hydraulic fluid can fiow through each of the lines in opposite directions for reversibly driving the hydraulic motor.

As indicated heretofore, the nozzle 1 and. propeller 2 in conjunction with the motor 5 are suspended outwardly of the hull lby means of the tubular suspension member. a and are rotated jointly as a unit in which they maintain fixed positions relative to each other. The tubularsus pension member 6 provides a pivotal axis disposed in a plane passing through the longitudinal axis of the nozzle ring 1 and the propeller 2.- The pivotal axis is positioned sothat it substantially passes through the turning disc of the propeller 2 thereby to provide for rotation of the entire unit externally of the hull through 369 degrees in an unimpeded condition with n. minimum application of torque for steering.

The suspension member 6 is tubular to provide for passage of the hydraulic lines 29, 31 therethrougb internally of the hull 4. Thetubular suspension member is connected to the hull t and the nozzle ring 1, which pref erably i also hollow, in a watertight connection as shown in FIG. 9; Thetubular member 6 is fixed to -and suspended from a rotatable turntable comprising a large diameter bearing sdwhich is preferably an annular ball bearing horizontally disposed internally of the. hull i. The annular bearing 33 is disposedcoaxially with and internally of a stationary ring 39fixed to the hull 4.

lrrorder to apply steering torque tothe nozzle rudder.

a tubular capstan lit, through which the hydraulic lines r 29, Ill extend, is secured'to the inner bearing 38 and is rotatably driven from a second capstan 42 vand-operably connected thereto by a chain 44. The second capstan L2 is angularly rotated selectively by an engine or motor 45 to which steering commands are selectively applied by a control system, not shown, for angularly rotating the entire underwater assembly or unit heretofore described to selected rudder angles. The cornmands are applied andthe motor dddriven in timed relationship with the application of hydraulic power to the hydraulic motor 5 from a pump means, not shown, inthe proper angular direction in either of-two opposite-directions'..

The known Kort nozzle rudder provides an increase of thrust over' linown propulsion apparatus depending on the vessels speed, for example 15 percent increase at high: speeds of the vessel and about 40 to 50 percent at' low speeds. In the nozzle rudder according to the present t invention the improved thrust is available to its full exr tent for propulsion and steering through. 360 degrees or" rudder angles. The possibility of using a large and slow turnin propeller permits obtainirn favorable ratios beb tween effective thrust and engine power. turnable unit for propulsion and steering is structurally just as sound, strong and seaworthy as the known Kort nozzle rudder. Forces required for turning the rudder can be kept reasonably small by proper mutual arrangement between the axis ofthe rudder and the turning disc of the propeller. 7

While a preferred embodiment of the invention has been shown and described, it will be understood that many modifications and changes can be made wtihin the true spirit and scope of the invention.

The jointly surfaces defining a substantially cylindrical portion in which the cross sectional area does not change materially along the longitudinal axis of said tubular nozzle ring, said cylindrical portion having a rear exit opening, said inner surfaces being enlarged relative to said cylindrical portion to define a water entrance portion having an entrance opening which is substantially larger in cross sectional area than said exit opening, a large diameter screw propeller freely rotatable in said tubular nozzle and having blades with tips and having a propeller turning disc substantially in an area of juncture of said water entrance portion and said cylindrical portion, the internal dimensions of said nozzle being such as to provide a small clearance between the tips of said propeller blades and said inner surfaces of said tubular nozzle ring, a reversible hydraulic motor operable at high pressures for selectively reversibly driving said screw propeller at comparatively low revolutions per minute, a shaft operably connecting said motor and said propeller and for rotatably supporting said propeller, a housing for said motor and said shaft having a configuration substantially faired to reduce water resistance and having at least rea-rWardly disposed outer surfaces converging toward said propeller disc, said housing rearwardly disposed converging outer surfaces defining in conjunction with the inner surfaces of said water entrance portion a continuously converging water entry zone between said entrance opening and the turning disc of said propeller, angularly spaced, fixed struts mounting said motor and motor housing forwardly of said propeller and mounting said shaft and propeller coaxially with said tubular nozzle ring, means comprising a tubular member pivotally supporting said tubular nozzle ring and said propeller motor, housing and shaft completely externally of said hull for angular rotation jointly as a unit, means comprising conduits disposed internally of said tubular member and extending to said motor for supplying hydraulic liquid under pressure to said motor for reversibly driving it selectively, and steering means for selectively angularly rotating said nozzle ring, propeller, motor, housing, and shaft as a unit for positioning said unit in given rudder angles.

2. Apparatus according to claim 1, in which said means pivotally supporting said tubular nozzle ring comprises a pivotal axis, disposed in a plane passing through the pivotal axis of said propeller and substantially through the turning disc of said propeller.

3. Apparatus according to claim 1, in which said housing for said hydraulic motor is disposed with its larger cross sections forward of said entrance position.

4. Apparatus according to claim 1, in which said means pivotally supporting said tubular nozzle ring comprises a bearing of comparatively large diameter for guiding angular movements of said nozzle ring and for transmitting horizontally the combined propulsive thrust of said screw propeller and said nozzle ring to said hull and for absorbing the vertical couple forces due to the distance between said bearing and the thrust forces acting substantially coaxially with the longitudinal axis of said tubular nozzle ring.

5. Apparatus according to claim 1, in which said means for rotating said means pivotally supporting said tubular nozzle ring comprises means for controllably rotating said tubular nozzle ring through 360 degrees in opposite directions.

6. Apparatus for combined propelling and steering of deep water vessels having a hull comprising an improved Kort nozzle rudder drive comprising, in combination, a profiled tubular nozzle ring comprising walls having airplane airfoil profiles and defining at least a well rounded front entering edge on said nozzle ring, said walls having inner surfaces defining a substantially cylindrical portion in which the cross sectional area does not change materially along the longitudinal axis of said tubular nozzle ring, said cylindrical portion having a rear opening, said inner surfaces being enlarged with distinctly increasing a.) cross sectional areas relative to said cylindrical portion to define a water entrance portion having an entrance opening which is substantially larger in cross sectional area than said exit opening, a large diameter screw proeller freely rotatable in said tubular nozzle and having blades with tips and having a propeller turning disc substantially in an area of juncture of said Water entrance portion and said cylindrical portion, the internal dimensions of said nozzle being such as to provide a small clearance between the tips of said propeller blades and said inner surfaces of said tubular nozzle ring, a reversible hydraulic motor operable at high pressures for selectively reversibly driving said screw propeller at comparatively low revolutions per minute, a shaft operably connecting said motor and said propeller and for rotatably supporting said propeller, a housing for said motor and said shaft having a configuration substantially faired to reduce water resistance and having at least rearwardly disposed outer surfaces converging toward said propeller disc, defining in conjunction with the inner surfaces of said water entrance portion a continuously converging water entry zone between said entrance opening and the turning disc of said propeller, said zone having an axiallength at least about fifteen percent of the overall longitudinal length of said tubular nozzle ring, angularly spaced, fixed struts at least one of which is hollow mounting said motor and motor housing forwardly of said propeller and mounting said shaft and propeller coaxially with said tubular nozzle ring, means comprising a tubular member pivotally supporting said tubular nozzle ring and said propeller motor, housing and shaft completely externally of said hull for angular rotation jointly as a unit, means comprising conduits disposed internally of said tubularrmernber and said one hollow strut for supplying hydraulic liquid under pressure to said motor for reversibly driving it selectively, and steering means for selectively angularly rotating said nozzle ring, propeller, motor housing, and shaft as a unit for positioning said unit in given rudder angles.

7. Apparatus for combined propelling and steering of deep water vessels having a hull comprising an improved Kort nozzle rudder drive comprising, in combination, a profiled tubular nozzle ring having walls having airplane airfoil profiles and defining rounded front and rear edges on said nozzle ring, said walls having inner surfaces defining a substantially cylindrical portion in which the cross sectional area does not change materially along the longitudinal axis of said tubular nozzle ring, said cyiin- V drical portion having a rear opening, said inner surfaces being enlarged with distinctly increasing cross sectional areas relative to said cylindrical portion to define a water entrance portion having an entrance opening which is substantially larger in cross sectional area than said exit opening, a large diameter screw propeller freely rotatable in said tubular nozzle and having blades with tips and having a propeller turning disc substantially in an area of juncture of said Water entrance portion and said cylindrical portion, the internal dimensions of said nozzle being such as to provide a small clearance between the tips of said propeller blades and said inner surfaces of said tubular nozzle ring, a reversible hydraulic motor operable at high pressures for selectively reversibly driving said propeller at comparatively low revolutions per minute, a shaft relatively shorter than said motor operably connecting said motor and said propeller and for rotatably supporting said propeller, a housing for said motor and said shaft having a torpedo-shaped configuration substantially faired to reduce water resistance and having at least rearwardly disposed outer surfaces converging toward said propeller disc, defining in conjunction with the inner surfaces of said water entrance portion a continuously converging water entry zone between said entrance opening and the turning disc of said propeller, angularly spaced, fixed struts at least one of'which is hollow mounting said motor and motor housing forwardly of said propeller and mounting said shaft and propeller coaxially with said tubular nozzle ring, means comprising a tubular member pivotally supporting said tubular nozzle ring and said propeller motor, housing and shaft completely externally of said hull for angular rotation jointly as a unit, means comprising conduits disposed internally hollow tubular member and said one of said struts for supplying hydraulic liquid under pressure to said motor for reversibly driving it selectively, and steering means for selectively angularly rotating said nozzle ring, pro- 10 711,884 10/02 Sjpstrorn 11542 2,139,594 12/38 Kort 1l542 X 2,445,369 7/48 Shields 115-34 2,714,866 8/55 Pleuger et al. 115-42 X FOREIGN PATENTS 18,661 1929 Great Britain.

FERGUS S. MIDDLETON, Primary Examiner. 

1. APPARATUS FOR COMBINED PROPELLING AND STEERING OF DEEP WATER VESSELS HAVING A HULL COMPRISING AN IMPROVED KORT NOZZLE RUDDER DRIVE COMPRISING, IN COMBINATION, A PROFILED TUBULAR NOZZLE RING HAVING WALLS HAVING AIRPLANE AIRFOIL PROFILES AND DEFINING AT LEAST A WELL ROUNDED FRONT ENTERING EDGE ON SAID NOZZLE RING, SAID WALLS HAVING INNER SURFACES DEFINING A SUBSTANTIALLY CYLINDRICAL PORTIONS IN WHICH THE CROSS SECTIONAL AREA DOES NOT CHANGE MATERIALLY ALONG THE LONGITUDINAL AXIS OF SAID TUBULAR NOZZLE RING, SAID CYLINDRICAL PORTION HAVING A REAR EXIT OPENING, SAID INNER SURFACES BEING ENLARGED RELATIVE TO SAID CYLINDRICAL PORTION TO DEFINE A WATER ENTRANCE PORTION HAVING AN ENTRANCE OPENING WHICH IS SUBSTANTIALLY LARGER IN CROSS SECTIONAL AREA THAN SAID EXIT OPENING, A LARGE DIAMETER SCREW PROPELLER FREELY ROTATABLE IN SAID TUBULAR NOZZLE AND HAVING BLADES WITH TIPS AND HAVING A PROPELLER TURNING DISC SUBSTANTIALLY IN AN AREA OF JUNCTURE OF SAID WATER ENTRANCE PORTION AND SAID CYLINDRICAL PORTION, THE INTERNAL DIMENSIONS OF SAID NOZZLE BEING SUCH AS TO PROVIDE A SMALL CLEARANCE BETWEEN THE TIPS OF SAID PROPELLER BLADES AND SAID INNER SURFACES OF SAID TUBULAR NOZZLE RING, A REVERSIBLE HYDRAULIC MOTOR OPERABLE AT HIGH PRESSURES FOR SELECTIVELY REVERSIBLY DRIVING SAID SCREW PROPELLER AT COMPARATIVELY LOW REVOLUTIONS PER MINUTE, A SHAFT OPERABLE CONNECTING SAID MOTOR AND SAID PROPELLER AND FOR ROTATABLY SUPPORTING SAID PROPELLER, A HOUSING FOR SAID MOTOR AND SAID SHAFT HAVING A CONFIGURATION SUBSTANTIALLY FAIRED TO REDUCE WATER RESISTANCE AND HAVING AT LEAST REARWARDLY DISPOSED OUTER SURFACES CONVERGING TOWARD SAID PROPELLER DISC, SAID HOUSING REARWARDLY DISPOSED CONVERGING OUTER SURFACES DEFINING IN CONJUNCTION WITH THE INNER SURFACES OF SAID WATER ENTRANCE PORTION OF CONTINUOUSLY CONVERGING WATER ENTRY ZONE BETWEEN SAID ENTRANCE OPENING AND THE TURNING DISC OF SAID PROPELLER, ANGULARLY SPACED, FIXED STRUTS MOUNTING SAID MOTOR AND MOTOR HOUSING FORWARDLY OF SAID PROPELLER AND MOUNTING SAID SHAFT AND PROPELLER COAXIALLY WITH SAID TUBULAR NOZZLE RING, MEANS COMPRISING A TUBULAR MEMBER PIVOTALLY SUPPORTING SAID TUBULAR NOZZLE RING AND SAID PROPELLER MOTOR, HOUSING AND SHAFT COMPLETELY EXTERNALLY OF SAID HULL FOR ANGULAR ROTATION JOINTLY AS A UNIT, MEANS COMPRISING CONDUITS DISPOSED INTERNALLY OF SAID TUBULAR MEMBER AND EXTENDING TO SAID MOTOR FOR SUPPLYING HYDRAULIC LIQUID UNDER PRESSURE TO SAID MOTOR FOR REVERSIBLY DRIVING IT SELECTIVELY, AND STEERING MEANS FOR SELECTIVELY ANGULARLY ROTATING SAID NOZZLE RING, PROPELLER, MOTOR, HOUSING, AND SHAFT AS A UNIT FOR POSITIONING SAID UNIT IN GIVEN RUDDER ANGLES. 